There are known casting machines used for the production of shaped ingots. The shaped ingot casting apparatus most generally employed is that known as a conveyer-type apparatus, which has ingot moulds or chills arranged on the endless chain of a coveyer. According to the construction of the ingot moulds or chills, such conveyer-type appratus can be used either for hot top casting or no-hot top casting. In the hot top casting apparatus it is common practice to use a hot top mounted on the top of an ingot mould for the purpose of containing feed or head metal and maintaining it molten while the metal in the ingot mould is solidifying. The metal in the hot top is above and in contact with the metal in the ingot mould so that as the metal in the ingot mould shrinks, the feed metal is fed down into the ingot body and thus prevents the formation of shrinkage cavities in the body of the ingot.
Even though it is possible to produce ingots of a good quality when practicing apparatus having ingot moulds provided with hot tops for the production of shaped ingots, there are some disadvantages inherent in such apparatus. One of these disadvantages consists in a considerable waste of starting metal contained in the hot tops. To provide a sufficient pressure of the molten metal required to avoid the formation of shrinkage cavities in the ingot, the molten metal of the hot top used for feeding of the ingot during solidification process must be of a large mass. For instance, up to 50% of the starting protector alloy is wasted as head metal required for feeding and formation of a protector when producing protectors with an apparatus provided with ingot moulds having hot tops.
Another disadvantage of apparatus provided with ingot moulds having hot tops resides in complexity of such ingot moulds. Since these hot tops are intended to delay solidification of feed or head metal contained therein, the hot tops must be provided with a heat-insulating liner which also results in complexity of their construction.
In addition, it is necessary to use special complex devices to extract finished shaped ingots out of such ingot moulds and it is then necessary to cut off the head from the articles so produced, which increases labour consumption during production of such articles.
Also known in the art is an ingot casting apparatus provided with open ingot moulds. One such apparatus comprises open ingot moulds hinged to an endless hauling chain of an inclined conveyer. The hauling chain is passed through toothed drums, one of which serves as driving drum.
In such prior art apparatus the open ingot moulds moving along the conveyer are passed in sequence under a tundish from which the molten metal is poured into the ingot moulds. The length of the conveyer and the travel speed of the ingot moulds are chosen such as to ensure complete solidification of the molten metal poured into the ingot mould during the period when the ingot mould moves from the metal pouring point to a deflecting toothed drum where the change of the conveyer branch motion direction occurs. When the upper branch of the conveyer chain is turned around the deflecting toothed drum, the ingot mould is turned around the hinges and tipped. As this takes place, the ingot mould is struck against a stop, therby providing knock-out of the casting from the ingot mould.
Such apparatus is characterized by simplicity and it has some disadvantages. Since shrinkage cavities are formed during solidification in the case when metal is poured into open ingot moulds, it is necessary to cast articles provided with considerable thickness shrinkage allowances that must be subsequently mechanically worked off, which results in an increased labour consumption and a considerably decreased metal-saving ratio.
Besides, such apparatus fails to provide articles of a predetermined size due to metal shrinkage during solidification.